| Hardware and OS | Siemens SX66 | Oppo A3s |
| Operating system | Microsoft Windows Mobile 2003 SE PocketPC | Android 8.1 (Oreo); ColorOS 5.1 |
| Processor | Intel Xscale PXA272 520 MHz | Octa-core 1.8 GHz Cortex-A53 |
| Chipset | | Qualcomm SDM450 Snapdragon 450 (14 nm) |
| GPU | | Adreno 506 |
| Internal memory | 128 MB RAM | 16 GB, 2 GB RAM |
| External memory | SDIO/MMC | microSD, up to 256 GB (dedicated slot) |
| Display | Siemens SX66 | Oppo A3s |
| Type | TFT | IPS LCD |
| Size | 3.5" inc | 6.2" inc |
| Resolution | 240 x 320 px | 720 x 1520 px |
| Touchscreen | resistive touchscreen | capacitive touchscreen |
| Screen-to-Body Ratio | 42.7% | 81.2% |
| Display area | 37.9 cm2 | 95.9 cm2 |
| Display aspect ratio | 4:3 (height:width) | 19:9 (height:width) |
| Pixel Density | 114 PPI | 271 PPI |
| Other | Downloadable logos | |
| Colors | 65K | 16M |
| Connectivity | Siemens SX66 | Oppo A3s |
| 2G Network | | GSM 850 / 900 / 1800 / 1900 - SIM 1 & SIM 2 |
| 3G Network | | HSDPA 850 / 900 / 2100 |
| 4G Network | | LTE |
| Wi-Fi | Wi-Fi 802.11b | Wi-Fi 802.11 b/g/n, WiFi Direct, hotspot |
| Network | GSM | GSM / HSPA / LTE |
| SIM card | Mini-SIM | Dual SIM (Nano-SIM, dual stand-by) |
| Bluetooth | Yes | 4.2, A2DP, LE |
| Edge | No | Yes |
| GPRS | Class 10 | Yes |
| GPS | No | Yes, with A-GPS |
| Speed | | HSPA 42.2/5.76 Mbps, LTE-A (2CA) Cat6 300/50 Mbps |
| USB | Proprietary | microUSB 2.0, USB On-The-Go |
| Camera | Siemens SX66 | Oppo A3s |
| Main camera | | 13 MP, Dual |
| Specs | | 13 MP, f/2.2, AF
-2 MP, f/2.4, depth sensor |
| Features | | LED flash, HDR, panorama |
| Video | | 1080p@30fps |
| Selfie camera | | 8 MP, Single |
| Multimedia | Siemens SX66 | Oppo A3s |
| 3.5 mm Jack | No | Yes |
| Radio | No | FM radio |
| Design | Siemens SX66 | Oppo A3s |
| Colors | Silver | Red, Dark Purple |
| Dimensions | 125 x 71 x 18 mm | 156.2 x 75.6 x 8.2 mm |
| Weight | 210 g | 168 g |
| Battery | Siemens SX66 | Oppo A3s |
| Battery life | Stand by time- Up to 200 h
Talking time- Up to 4 h
| |
| Battery capacity | | 4230 mAh, Non-removable Li-Ion |
| Other | Siemens SX66 | Oppo A3s |
| Release date | 2004, Q4 | 2018, July |
| Sensors | Infrared port | Accelerometer, proximity, compass |
